South Sudan is a landlocked country, with tropical rainforest, swamp and grassland regions. Once the largest and one of the most geographically diverse states in Africa, split into two countries in July 2011 after the people of the south voted for independence. The mainly Christian and animist people had for decades been struggling against the rule of the Arab Muslim north. However, various outstanding secession issues, especially the question of shared oil revenues and the exact border demarcation, have continued to fuel brutal conflicts. Two rounds of north-south civil war cost the lives of millions of people and displaced a large number of people from the Darfur region.